Why Do Boats Float?



Why do boats float? No matter what size they are, big or small, boats float on top of the water. How do they do it?

Cyrus tells an incredible story about the ancient Greek scientist, Archimedes, and explains why boats float on top of water.


Eureka!

Boats of all sizes float on top of the water in oceans, lakes and rivers all around the world. Everything from small dhow boats off the coast of Zanzibar to giant freighters docking into a harbor stay safely above the water. How do they stay on top of the water and not sink? Have you ever heard someone shout, “Eureka!” when they’ve solved a difficult problem? Many, many years ago, there was a famous Greek scientist named Archimedes that shouted, “Eureka!” and he helped us understand how boats float.

So the story goes…

The king hires a crafty craftsman.

The king had a crown made out of a chunk of pure gold by a local craftsman. He thought the craftsman stole some of the gold by swapping it for silver that wasn’t worth very much.

Unfortunately, the king couldn’t prove it, so he asked Archimedes to help him.


Archimedes definitely thinks better when he’s in the bath.

Archimedes couldn’t figure it out until one day, when he sat down in his bath, the water level went up.

He knew he had a way he could solve the king’s question and was so excited, he jumped out of the bath and ran down the street shouting, “Eureka! Eureka!”


Which water level is highest?

He weighed the crown, a chunk of gold and a chunk of silver. He put each of them in the water one by one, and wrote down how high the water level rose with each object. Using math, he discovered that the crown did not weigh as much as the gold, but did weigh more than the silver! The king was right! The craftsman did cheat him!

Buoyancy and how it helps boats float

Archimedes had discovered something called, “buoyancy” and it’s the reason boats float.

The boat is able to float because the amount of water that’s pushed away weighs more than the boat itself.

If something floats, it’s because the amount of the water that is pushed away weighs more than the object on top. If the amount of water that’s pushed away weighs less than the object on top, the object sinks!

 


Archimedes was an amazing person! He would have made a great Inspero Intelligence Officer, right?


Credits

Why Do Boats Float?

Executive Producers
Jim Demetriades and Nikos Iatropoulos

Directed by
Joseph Rohrs and Luke Gschwend

Hosted by
Cyrus Rohrs

Written and edited by
Joseph Rohrs

Production Assistant
Gwynne Rohrs

Animation
Jonathan Reaux

Footage

Videoblocks

Resources

The story of Archimedes was written by Martyn Shuttleworth and can be found here: https://explorable.com/displacement-experiment

http://www.scientificamerican.com/article/bring-science-home-how-metal-boats-float/

Images from Freepik.com

Bust of Archimedes Photo:

Giovanni Dall’Orto of Luciano_Campisi, Monument to Archimedes

3d Models

turbosquid.com

Music

Licensed through Audiojungle: “Adventure” by Allegro120

Sound Effects

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